Catheters, such as intravascular catheters, are commonly constructed of multi-layer tubular members including multiple layers of polymeric material. The polymeric material for one layer of the multi-layer tubular member may be chosen for certain desired characteristics, while the polymeric material for another layer of the multi-layer tubular member may be chosen for other certain desired characteristics. In some instances, the polymeric material of the first layer may be incompatible with the polymeric material of the second layer. For example, the polymeric material of the first layer may not be readily bonded or adhered to the polymeric material of the second layer. In such instances, an intermediate layer or tie layer may be placed between the first layer and the second layer. The intermediate or tie layer may readily bond or adhere to each of the first layer and the second layer, thus “tying” the first layer to the second layer.
It is generally known that fluoropolymers, such as polyvinylidene fluoride (PVDF), are generally not bondable to other polymeric materials, such as polyamide, polyether block amide, polyurethane, polyethylene and polyester. Thus, if it is desired to use a fluoropolymer, such as polyvinylidene fluoride (PVDF) as one layer of a multi-layer catheter tubing, and a non-compatible polymer, such as polyamide, polyether block amid, polyurethane, or polyester, as another layer of the multi-layer catheter tubing, then a tie layer is necessary to prevent delamination of the fluoropolymer layer from the other polymer layer.
The inclusion of the intermediate or tie layer in the catheter tubing adds thickness to the tubing, as well as adds additional cost to the manufacture of the catheter tubing. For instance, in addition to the additional cost of the tie layer material, an additional extruder would be necessary in order to co-extrude the tie layer with the inner and outer layers of the tubular member.
It would be advantageous to manufacture a catheter tube having a fluoropolymer layer, such as polyvinylidene fluoride (PVDF), directly bonded to another polymer layer without the need for an intervening tie layer disposed between the fluoropolymer layer and the other polymer layer. Thus, such catheter tubing may benefit from the inclusion of a fluoropolymer layer without the concern of the fluoropolymer layer delaminating from the other polymeric layer of the catheter tube.